Apparatus for producing corrugated dihedral blanks

ABSTRACT

Apparatus for producing a dihedral element with inwardly projecting corrugations. The uncorrugated dihedral or sheet metal blank is worked by punch and die members including a pair of lateral punches, having shaping edges in a common plane at an angle to each other and provided with adjacent sunk ends; a central punch between said ends; a die of complimentary configuration together with holding and retaining means; and means for relative synchronized and coordinate motions of the several tools.

United States Patent Alleaume et al.

[4 1 Aug. 29, 1972 [54] APPARATUS FOR PRODUCING CORRUGATED DIHEDRALBLANKS [72] Inventors: Jean H. Alleaume, Saint-Cloud; Gilbert C. F.Fournier, Le Havre, both of France [73] Assignee: Technigaz, Paris,France; by said Alleaume [22] Filed: July 17, 1969 [21] Appl. No.2842,482

[30] Foreign Application Priority Data Dec. 31, 196 8 France ..68182929[52] 0.8. CI ..72/399, 72/452 [51] Int. Cl. ..B2lj 13/02 [58] Field ofSearch ..72/399, 379, 395, 452, 381, 72/380, 385, 313, 305, 297, 356

[56] References Cited UNITED STATES PATENTS 1,561,556 11/1925 McMahoh..72/399 2,010,996 8/1935 Junkers ..72/395 2,272,547 2/ 1942 COOrdCS..72/ 399 2,798,388 7/1957 ECkOld ..72/395 3,025,905 3/1962 Haen'..72/379 3 144,069 8/ 1964 Rutter ..72/ 379 3,425,260 2/ 1969 Anderson..72/452 3,499,308 3/ 1970 Ford ..72/452 Primary ExaminerCharles W.Lanham Assistant ExaminerGene P. Crosby Att0rneyNolte and Nolte [57] 9ABSTRACT Apparatus for producing a dihedral element with inwardlyprojecting corrugations. The uncorrugated dihedral or sheet metal blankis worked by punch and die members including a pair of lateral punches,having shaping edges in a common plane at an angle to each other andprovided with adjacent sunk ends; a central punch between said ends; adie of complimentary configuration together with holding and retainingmeans; and means for relative synchronized and coordinate motions of theseveral tools.

14 Claims, 6 Drawing Figures mimmausgslsrz 31586320 sum 2 0F 5 INVENTORSJEAN H. ALLEAUME BYGILBERT C.F. FOURNIER ATTORNEYS PATENTEDauszs I972 Mi3 OF 5 INVENTORS JEAN H. ALLEAUME GILBERT C.F. FOURNIER BY 7 m 17mATTORNEYS PATENTED M1829 I972 SHEET U 0F 5 INVENTORS JEAN H. ALLEAUMEGlLBE RT C. F. FOURNIER ATTORNEYS PATENTEmuszs 1912 I 3.686, 920

sum 5 or s 1 I I x ,116

INVENTORS JEAN H. ALLEAUME GILBERT C F. FOURNIER BY 7 m A 7 W ATTORNEYSAPPARATUS FOR PRODUCING CORRUGATED DIHEDRAL BLANKS The present inventionrelates to apparatus for producing corrugated corner pieces (dihedral)for contamers.

Corrugated corner pieces are already known, which are made for instanceof sheet metal, and are provided with at least one corrugationprojecting from the inner side and on each face of the dihedral angle.Such a corrugation has two corrugation portions, one on each of the twoadjacent faces of the dihedron. Such pieces which may be provided withseveral of the said parallel corrugations, for instance in spacedrelationship, and which may have any desired length in a directionparallel to the crest of their dihedron, are used in particular asconnecting or corner elements between two walls of an enclosure.

The apparatus comprises on the one hand at least one pair of movablelateral punching knives or like male forming tools for formingrespectively the two corrugation portions in the two walls or faces ofthe aforesaid dihedron and at least one movable central punching toolfor forming the intermediate projecting dihedral portion, and on theother hand at least one movable die or like female forming tool havingpreferably a deformable or variable configuration, as well as holding orretaining means for preventing any relative sliding displacement of thesheet metal blank being worked with respect to the said tools.

The invention will be better understood and other objects,characteristics, details and advantages thereof will appear as thefollowing explanatory descriptions proceeds with reference to theappended diagrammatic drawings given solely by way of exampleillustrating one form of embodiment of the invention and wherein FIG. 1is a perspective view of the corner piece according to the invention,the dihedral angle of which forms substantially a right angle;

FIG. 2 is a diagrammatic profile or side view of a corner piece with anobtuse dihedral angle;

FIG. 3 is a diagrammatic view of the piece of FIG. 2 developed in asingle plane showing the various folding lines;

FIG. 4 is an elevational view of a forming device according to theinvention seen in vertical section upon the line IV-IV of FIG. 5, atright angles to the crest of the aforesaid dihedron;

FIG. 5 is a vertical axial sectional view taken along the line V-V ofFIG. 4; and

FIG. 6 is a fragmentary cross-sectional view of the same device takenalong the lines VI-VI of FIG. 4, wherein the movable members are shownin the same position as in FIG. 5.

According to the form of embodiment illustrated in FIG. 1, the cornerpiece of sheet metal 1 is folded so as to form a dihedron, the angle 0of which is shown as a substantially right angle. Each face of thisdihedron is provided with a substantially dihedral corrugation or wave2, 2 projecting towards the interior of the dihedron and extending atright angles to the crest 3 of the latter, so as to be symmetrical withrespect to a plane extending at right angles to the crest 3 andcontaining the crest lines of the two waves 4, 4'. The piece 1 may ofcourse be provided with several parallel waves 2, 2' spaced along thecrest 3 or ZZ.

Each crest line 4, 4 terminates near crest 3 at a point B, B where itbifurcates so as to divide into two divergent, inwardly convex foldshaving crest lines BA, BA and BA, B'A'. The crest ZZ meets thesedivergent fold lines respectively, at points A, A of intersectionbetween the crest and the fold lines. From each end of the crest linesB, B there also extends a third fold, having crest line BC, and B'C andwhich is inwardly concave and re-entrant and the ends C and C of whichare connected to the said points A, A, respectively by still furtherconcave folds with crest lines CA, CA and C'A, C'A', the points C, Cbeing joined by a convexfold line C C.

FIG. 2 is an elevational view in profile of a folded corner piecesimilar to the piece 1 of FIG. 1, but having an obtuse dihedral angle,whereas FIG. 3 shows the plane development of the piece of FIG. 2 withreference figures corresponding to those of FIG. 1. The concave-foldlines at the base of the waves are denoted by X A X and Y AY, while thecrest lines are denoted by Y, B and Y B. It is seen that the commonconnecting surface between the two corrugations 4 and 4 in the angle ofthe dihedron is a skew polyhedral surface with adjacent triangularfacets, comprising two reentrant dihedral portions B C A A and B C A Aforming respectively the mutually confronting, terminal surfaces of thetwo waves and an intermediate projecting dihedral portion C C A A,respectively adjacent to the two re-entrant dihedral portions andinterconnecting the latter. In order to avoid any extension of materialoutside the dihedron, that is projecting on its external faces, it isnecessary that the points C and C should not lie outside the plane ofthe faces of the dihedron 1, that is they may at most occupy theposition shown in FIG. 2, and therefore be located in either plane ofthe dihedron. In FIG. 2 it is assumed that the angle of the corrugations2 and 2 is zero, i.e. the side or lateral faces of these waves arebrought together so as to coincide or be parallel to one another.Assuming,

Since in order to obtain FIG. 3 from FIG. 2 the sheet must be entirelyunfolded, the angle CAC' which was coincident with the dihedral angleXAX' 0 is flat and unfolded, so that the angle CAC' may be considered tobe the flat unfolded view of the dihedral angle 0. Therefore Thefollowing condition must of course be fulfilled:

or again WlIOI'CfIOIIl it. finally follows:

The intermediate projecting dihedral crest portion CC, interconnectingthe two waves 2, 2' comprises in its crest a substantially centralimprint or depression 4a which is approximately dihedral and extendstransversely of the said crest and over at least part of the height ofthe said portion.

FIGS. 4 to 6 illustrate the forming or shaping device for obtaining acomplete corrugation 2, 2 in a sheetmetal element 1 previously folded toform a dihedron, the principle upon which this device is based being ofcourse applicable to simultaneous shaping of several such corrugations,parallel spaced on one and the same sheet previously folded to form adihedron. The device is for instance adapted to be mounted on a foldingpress, the stationary clamping table of which is denoted by thereference numeral 5, while the movable plate of the press is shown at 6and is rigid with the vertical slide 7 of the press. The table 5, whichis for instance substantially horizontal, carries a stationary structure8 forming a clamping pad or the like which itself carries a die 9 whoseupper surface has a configuration corresponding to the internal finishedshape of the sheetmetal blank 10 folded to form a dihedron andcorrugated to provide the raised and sunk portions of the finishedcorner piece 10.

The device as a whole is preferably substantially symmetrical withrespect to the bisecting plane of the dihedron of the finished cornerpiece placed in the device and with respect to the normal mediallongitudinal plane of the said corrugations.

The die 9 is composed of two elements or half-dies 9a, 9b arrangedsubstantially symmetrically with the plane extending at right angles tothe crest of the said dihedron and passing through the crest lines ofthe said corrugations, the said half-dies being symmetrically movable inopposite directions with respect to one another, so as to be capable ofsimultaneously moving towards or apart from one another in a directionat right angles to the said plane. The hollow form or mould for formingeach wave 2, 2' is therefore divided into two symmetrical half-forms 11aand 11b as shown in FIG. 6. Similarly, the hollow form for forming theintermediate projecting dihedral crest portion C C is also separatedinto two symmetrical portions 12a, 12b as shown in FIG. 5. Each half-die9a, 9b is movable in circular translation and is connected to thestationary base structure 8 through the medium of a plane articulatedcontrol system forming preferably an articulated parallelogram or likeguiding mechanism. Such mechanism for each half-die is shown ascomprising a pair of links, journalled pins or like rigid members 13,each having two ends, articulated respectivelyon the half-die and on thestationary structure 8 by means of pivot pins l4, 14. In the form ofembodiment illustrated in FIGS. 4 and 5, each articulated connection isobtained through the medium of, e.g., two sets of three substantiallyco-axial or aligned crank-shafts 15, the crankpins or journals of whichare rotatably mounted in suitable bearings in the stationarystructure 8and the pivot pins 14 of which are rotatably mounted in suitablebearings rigid with the relevant half-die 9a, 9b.

The maximum horizontal clearance position of the two half-dies 9a, 9b,as shown in FIG. 5, is ad vantageously determined or definedrespectively by two stationary stops 16, 16', which may be solid withthe stationary structure 8 and each constituted preferably by aninclined plane wall surface cooperating with a corresponding plane wallsurface of the respective associated half-die 9a, 9b. In this positionof maximum clearance between the two half-dies each plane containing theaxes of the two pivot pins 14, 14 of an articulated connecting member 13of a half-die is preferably inclined to the other half-die, that is inthe direction of initiation or starting of the motion of the twohalf-dies towards one another, in order to promote the starting of thismotion.

The two mutually confronting waves of each corrugation of the dihedralcorner piece 10 are pressformed, respectively, by lateral punchingmembers 17a and 17b, while the intermediate connecting portion ispressed-formed by a central punch-member 18.

Return means, eventually automatic, such as springs or compressed-fluidactuating devices are advantageously provided to preferablysimultaneously move the said half-dies back to their initial position ofmaximum clearance. In FIG. 5 such a return spring 33 is shown to beplaced between the two half-dies so as to bear against each of thelatter in a suitable embedment recess 34, 34'. In a modified embodiment,the return mechanisms may also act upon the elements 13 or upon theirpivot pins.

Each lateral punching member 17a, 17b is rigid with a drivenpunch-carrying block 19a, 19b resting in guided sliding or rollingcontact upon a corresponding guiding wall 20a, 20b of the die 9, i.e. ofthe respective half-die 9a, 9b. Each of these guiding walls has apreferably substantially planar surface at right angles to the die wall21a or 21b carrying an associated face of the dihedron of the cornerpiece 10 and parallel to the crest of the latter. The correspondingsurface of each block 19a, 19b which is in contact with the associatedplane face 20a, 20b of the die is also preferably plane.

Central punching member 18 is rigid with a driving punch-carrying block22. This block is movable in a direction parallel to the bisecting planeof the dihedron of the corner piece 10, i.e., in this case,substantially vertically, be resting in sliding or rolling contactsimultaneously upon the two lateral punch-carrying blocks 19a and 19b,respectively along a contact interface or separating surface 23a, 23bwhich is substantially planar, parallel to the crest of the saiddihedron and inclined to each associated corresponding guiding wall ofthe die 9, so that the combined motions of the three tools 17a, 17b and18 are geometrically and kinematically compatible with the configurationof the portions to be shaped. The central punch-carrying block 22 ismade rigid with the press upper plate 6 which during its downward motionmoves nearer to the table 5 and during its upward motion moves aparttherefrom.

Guiding means are provided respectively between .t ,e sh-si ymk skal a191 the one hand and the die 9 and the central punch-carrying block on theother hand. These guiding means are advantageously constituted by atleast one slideway or like sliding or rolling path 24, e.g. of theslot-and-tongue type, such as illustrated in FIG. 6 which shows theguiding of the lateral punch-carrying block 19a on the centralpunchgcarrying block 22.

Each die 9 may of course comprise of a die-carrying block supporting thedie proper.

The combined motions of the three punches or tools 17a, 17b, 18 and ofthe two half-dies or die-carrying blocks 9 must ensure, without relativesliding or mutual displacement of the sheet-metal element with respectto these half-dies, the application of the sheet on the one hand againstthe punches and on the other hand against the half-dies, so that uponcompletion of the motions the punches and the half-dies perfectlyconfine the sheet. Holding or retaining means are provided to preventany general or total slipping or displacement of the sheet with respectto the punches and the half-dies for the whole duration of the shapingoperation. These means are advantageously constituted by at least twopairs of blank or sheet hold-down clamps 25a, 25b and 25'a, 25'b placedrespectively on either side of each lateral punch-member 19a, 19b andensuring the clamping of the sheet against the die 9 during theapproaching motion of the punch-members towards the said die by bearingon the one hand upon the said sheet and on the other hand against thelateral punchcarrying blocks 19a, 19b, preferably through the medium ofresilient elements or pads such as springs 26 or of hydraulic orpneumatic actuating devices.

Since each lateral punch-carrying block 19a, 19b extends substantiallyover the whole width of the central punch-carrying block 22 (see FIG.6), it cannot follow the motion of the half-dies 9a, 9b towards eachother, the said motion being automatic and caused solely by the verticaldownward pressing force exerted by the press plate 6. It is thereforenecessary to interpose between each blank hold-down clamp and the sheet10 to be worked an intercalated plate 27, 27 in sliding or rollingcontact with the said blank hold-down clamp, the two plates located onone and the same side of the lateral punch-members 17a, 17b beingpreferably rigid with one another and forming a bent or angle element27, 27 forming a dihedron corresponding in shape to that of the sheet10. In case of sliding contact between the element 27, 27 and the saidblank hold-down clamps, this contact may take place through the mediumof lubricated plane surfaces, whereas in case of rolling contact thelatter can be obtained by interposing rolling members such as balls,rollers or the like.

In order to enable, upon completion of the shaping operation, thefreeing of the finished corner piece 10 from the device and the placingof a new blank to begin a new operating cycle, means are provided forautomatically moving off the lateral punch-members and the associatedblank hold-down clamps of the aforesaid die, during the off motion ofthe central punchmember, the control of these means being preferablyinterdependent with the off motion of said central punch-member. Thesemeans are preferably constituted by the bearing plates of the said blankhold-down clamps which are made rigid with one another in pairs a, 25band 25'a, 25'b so as to form two one-piece or solid bearing plates 25,25' bent respectively to form a dihedron corresponding .in shape to thatof the sheet 10 stem.

and both connected unilaterally to the central punchcarrying block 22,so as to be raised and suspended by the latter in its maximum clearanceposition from the die, but enabling them to freely move towards thecentral punchcarrying block. According to one form of embodiment, eachbent bearing plate 25, 25' is made rigid through the medium of itsprojecting bend with a stem or the like 28, 28' normal to the surface ofthe said plate and parallel to the bisecting plane of the said dihedron,i.e. substantially vertical. Two such stems are shown, one on eitherside of the central punch-member 18. Each stem is mounted so as to befreely slidable in the central punch-carrying block 22 and is providedwith means for stopping its outward, i.e. downward, motion, the saidmeans consisting of a head, a collar, a shoulder, a flange or a pinprojecting radially and adapted to make contact with a similar stop orshoulder rigid with the central punch-carrying block. According to theform of embodiment illustrated, each stem 28, 28' freely slides in asubstantially vertical bore 29, 29 provided in the punch-carrying block22, the said bore opening at its lower end on the outside and at itsupper end into a cylindrical or prismatic cavity 30, 30' (FIG. 5) of thepunch-carrying block 22. The upper end of each said stern engages intothe associated cavity and is advantageously provided at its end with ahead or the like 31, 31' protruding laterally and mounted with clearanceso as to be freely movable inside the associated cavity. Each head isadapted to engage, at the end of the downward travel of the associatedstem, the lower bottom 32, 32 of the corresponding cavity, thus limitingthe magnitude of the outward motion of the Bach intercalated plate 27,27 is advantageously connected to the corresponding bearing plate 25, 25of the associated blank hold-down clamps so as to automatically moveaway from the die during the off motion or withdrawal of the saidhold-down clamps while at the same time being freely movable in adirection parallel to the said bearing plate. To this end, eachintercalated plate is connected to the associated bearing plate by meansof, for instance, a sliding articulation constituted by at least one pin35 provided with a head rigid with the intercalated plate and traversinga longshaped opening 36 provided in the bearing plate in which it ismovable.

This device operates as follows initially, the slide 7 of the press andthe associated press plate 6 are raised to their maximum upper position,so that the central punch-carrying block 22 occupies itsmaximum upperposition in which the blank hold-down clamps 25, 25 are suspended bymeans of the stems 28, 28' from the central punch-carrying block 22 awayfrom the die 9, while the intercalated plates 27, 27' are suspended fromthe hold-down clamps by means of their pins 35 away from the die 9. As aresult, the lateral punch-carrying blocks 19a, 19b which normally restat least partially upon the said hold-down clamps are also raised by thelatter away from the die 9 by sliding along the plane surfaces 20a, 20bof the latter. On the other hand, the two half-dies 9a, 9b are movedaway from one another by spring 33 until they abut against the surfaces16, 16' of the base 8. A sheet-metal blank 10 previously folded in theshape of a dihedron is then arranged on the die 9. The press plate 6and, therefore, the central punch-carrying block 22 is caused to movedownwards, whereby the block 22 acts simultaneously upon the lateralpunch-carrying blocks 19a, 19b, compelling them to move towards the dieand perform the shaping of the sheet 10. At the same time, under theaction of the pressure exerted by the central punch-carrying block 22upon the die 9 through the medium of the lateral punch-carrying blocks19a, 19b, the two half-dies 9a and 9b are compelledto move progressivelytowards one another during the shaping operation, for instance untilthey engage with one another and/or with the base 8. As soon as theblank hold-down clamps 25, 25' guided by the stems 28, 28' engagerespectively the bent intercalated plates 27, 27 which themselves are incontact with the sheet 10, the stems 28, 28' are immobilized but thedownward motion of the central punchcarrying block 22 is not stoppedowing to the fact that the cavities 30, 30' have sufiicient free heightto allow the necessary upward relative displacement of the slums 28while central punch-member 18 moves in downward direction. During thisdownward motion, the blank hold-down clamps are compressed andeventually resiliently collapse while they enable the lateralpunch-carrying blocks to continue to move downward.

The inclination of the two sliding planes 23a, 23b is selected so thatthe driving-in motions of the three punch-members, directed at rightangles to the base plane of the sheet to be shaped, take place accordingto a suitably selected ratio which is compatible with the desiredshapes. On the other hand, the tilting guiding mechanism 13-15 of thetwo half-dies 9a, 9b imparts to the latter the necessary degree offreedom to enable them, through the medium of the sheet pressed by thehold-down clamps, to conveniently combine their motions with thedownward motions of the three punchmembers.

During the upward motion of the plate 6 the various movable parts moveaccording to a sequence reverse to that previously described.

The sheet is pre-formed between the three punchmembers 17a, 17b and 18,to a shape corresponding to minimum elongation of the material. Uniformshaping of the sheet is facilitated as two half-moulds are provided inthe connecting zone at the top of the half-dies 9a, 9b.

The corrugated corner piece 10 thus obtained is not yet the completedpiece, i.e. the piece in its finished state. At the end of the shapingoperation, the dihedral angle generally exceeds the dihedral angle to beobtained finally. A complementary finishing machine imparts to the topof the small wave C C connecting the two main waves 2, 2 a slightdeformation or imprint 4a obtained by means of a punch-member arrangedat right angles to the crest of the said small wave and which acts so asto reduce the dihedral angle, thus imparting additional resiliency orsuppleness allowing for angular variation of the dihedron.

The corner piece obtained may also be subjected, by means of acomplementary tool assembly, to a further deformation in order to modifythe shape of the wave obtained on each face or half-plane of thedihedron. This deformation may be the same for both half-planes or facesor alternatively, may be different when it is required to interconnectwaves of unequal magnitude located in different planes.

It is to be understood that the invention should not be construed aslimited to the embodiments described and shown which have been given byway of illustration only, as many modifications and alterations may beresorted to by those skilled in or conversant with the art withoutdeparting from the gist or scope of the invention. In particular itcomprises all the means forming technical equivalents to the meansdescribed as well as their combinations, if they are carried out or putinto practice according to the spirit, principles and teachings of theinvention as defined in the appended punch-members each having asubstantially straight shaping edge, both punch members being arrangedso that said shaping edges are located substantially in a common planeat an angle to each other and being provided with adjacent sunk ends,said lateral punch-members constituting male forming tools, and at leastone movable central dihedral punch-member intermediate said adjacentsunk ends, said central dihedral punch member having a substantiallystraight shaping edge in said common plane and on the other hand atleast one movable die constituting a female forming tool having avariable configuration combined with and complementary to that of saidpunch-members in order to cooperate therewith, as well as blank holdingand retaining means and means for interdependent automatic controlproviding relative synchronized and coordinate motions of said male andfemale forming tools in forced positive mutual guiding relationship sothat said punch-members move together in translation in parallelrelation to said common plane.

2. A device according to claim 1, wherein said die is formed with a pairof concave dihedral recesses located in registering relationship withsaid lateral punch-members and each one comprising a blank supportingside and a punch-member guiding side, said sides extending at rightangles to said common plane and wherein each lateral punch-member isrigid with a driven lateral punch-carrying block resting in movablecontact-upon the guiding side of the associated recess.

3. A device according to claim 2, wherein said central punch-member isrigid with a driving central punch-carrying block movable in parallelrelation to said common plane by resting in movable contactsimultaneously against said two lateral punch-carrying blocks,respectively, along a contact interface which is substantially planar,extending in a direction parallel to said common plane and inclined withrespect to each aforesaid corresponding associated guiding side of saiddie.

4. A device according to claim 3, comprising guiding means, between saidlateral punch-carrying blocks on the one hand and said die and saidcentral punch-carrying block on the other hand, said guiding means beingconstituted respectively by at least one slideway of the slot-and-tonguetype.

5. A device according to claim 1, wherein each die is composed of twoelements forming half-dies substantially symmetrical with respect tosaid common plane, said half-dies being symmetrically movable inopposite directions with respect to one another.

6. A device according to claim 5, wherein each halfdie is movable incircular translation and connected to a stationary base structureforming a clamping plate through the medium of a plane linkage controlsystem consisting of a hinged parallelogram forming a parallel motionguiding mechanism, comprising two opposite rotatable sides which areconstituted by at least two links pivoted respectively to said half-dieand stationary structure.

7. A device according to claim 6, comprising a pair of stationary stopsrigid with said stationary structure and adapted to set a maximumclearance position of said two half-dies and wherein each one of saidlinks is pivoted through two pivot axes lying in a plane which isinclined in said maximum clearance position towards said plane ofsymmetry of said die in the direction of initiation of the motion of thetwo half-dies towards each other.

8. A device according to claim 2, wherein said blank holding andretaining means are constituted by at least two pairs of blank hold-downclamps arranged respectively on either side of each lateral punch-memberand bearing against said lateral punch-carrying blocks through themedium of pushing elements.

9. A device according to claim 8, wherein each one of said blankhold-down clamps is engageable with an intercalated plate in movablecontact with said holddown clamp, and interposed between the latter andsaid die, both plates located on the same side of said lateralpunch-members being rigid with one another and forming an element bentto a dihedron.

10. A device according to claim 9, wherein each aforesaid hold-downclamp is provided with a bearing plate, said bearing plates being rigidwith one another by pairs so as to form respectively two bearing platesbent in the shape of a dihedron and connected respectively unilaterallyto said central punch-carrying block, so as to be raised and suspendedfrom the latter in said position of maximum clearance while at the sametime allowing them to freely move towards the latter.

11. A device according to claim 9, wherein each bent bearing plate ismade rigid by its projecting bend with a rod normal to its surface andlocated in the bisecting plane of said dihedron and mounted freelyslidable in said central punch-carrying block, said rod comprising meansfor stopping its outward motion, constituted by a carrying block, bothrods being arranged on either side of said central punch-member.

12. A device according to claim 1, said punch-members beingsubstantially symmetricalwith respect to the bisecting plane of saiddihedron.

13. A device according to claim 5, wherein automatic return means areprovided to simultaneously move said half-dies back to their initialposition of max imum clearance.

14. A device according to claim 9, wherein each intercalated plate isconnected to the bearing plate of the associated blank hold-down clamps,so as to automatically move away from said die during the withdrawal ofsaid hold-down clamps, while at the same time being freely movable inparallel relation to said bearing plate.

1. In a manufacturing device for shaping a dihedral sheet metal blankand constituting a folding tool assembly comprising punches and dies andadaptable to a folding press-like shaping machine, the improvementconsisting in that said device comprises on the one hand at least onepair of movable lateral dihedral punchmembers each having asubstantially straight shaping edge, both punch members being arrangedso that said shaping edges are located substantially in a common planeat an angle to each other and being provided with adjacent sunk ends,said lateral punchmembers constituting male forming tools, and at leastone movable central dihedral punch-member intermediate said adjacentsunk ends, said central dihedral punch member having a substantiallystraight shaping edge in said common plane and on the other hand atleast one movable die constituting a female forming tool having avariable configuration combined with and complementary to that of saidpunch-members in order to cooperate therewith, as well as blank holdingand retaining means and means for interdependent automatic controlproviding relative synchronized and coordinate motions of said male andfemale forming tools in forced positive mutual guiding relationship sothat said punchmembers move together in translation in parallel relationto said common plane.
 2. A device according to claim 1, wherein said dieis formed with a pair of concave dihedral recesses located inregistering relationship with said lateral punch-members and each onecomprising a blank supporting side and a punch-member guiding side, saidsides extending at right angles to said common plane and wherein eachlateral punch-member is rigid with a driven lateral punch-carrying blockresting in movable contact upon the guiding side of the associatedrecess.
 3. A device according to claim 2, wherein said centralpunch-member is rigid with a driving central punch-carrying blockmovable in parallel relation to said common plane by resting in movablecontact simultaneously against said two lateral punch-carrying blocks,respectively, along a contact interface which is substantially planar,extending in a direction parallel to said common plane and inclined withrespect to each aforesaid corresponding associated guiding side of saiddie.
 4. A device according to claim 3, comprising guiding means, betweensaid lateral punch-carrying blocks on the one hand and said die and saidcentral punch-carrying block on the other hand, said guiding means beingconstituted reSpectively by at least one slideway of the slot-and-tonguetype.
 5. A device according to claim 1, wherein each die is composed oftwo elements forming half-dies substantially symmetrical with respect tosaid common plane, said half-dies being symmetrically movable inopposite directions with respect to one another.
 6. A device accordingto claim 5, wherein each half-die is movable in circular translation andconnected to a stationary base structure forming a clamping platethrough the medium of a plane linkage control system consisting of ahinged parallelogram forming a parallel motion guiding mechanism,comprising two opposite rotatable sides which are constituted by atleast two links pivoted respectively to said half-die and stationarystructure.
 7. A device according to claim 6, comprising a pair ofstationary stops rigid with said stationary structure and adapted to seta maximum clearance position of said two half-dies and wherein each oneof said links is pivoted through two pivot axes lying in a plane whichis inclined in said maximum clearance position towards said plane ofsymmetry of said die in the direction of initiation of the motion of thetwo half-dies towards each other.
 8. A device according to claim 2,wherein said blank holding and retaining means are constituted by atleast two pairs of blank hold-down clamps arranged respectively oneither side of each lateral punch-member and bearing against saidlateral punch-carrying blocks through the medium of pushing elements. 9.A device according to claim 8, wherein each one of said blank hold-downclamps is engageable with an intercalated plate in movable contact withsaid hold-down clamp, and interposed between the latter and said die,both plates located on the same side of said lateral punch-members beingrigid with one another and forming an element bent to a dihedron.
 10. Adevice according to claim 9, wherein each aforesaid hold-down clamp isprovided with a bearing plate, said bearing plates being rigid with oneanother by pairs so as to form respectively two bearing plates bent inthe shape of a dihedron and connected respectively unilaterally to saidcentral punch-carrying block, so as to be raised and suspended from thelatter in said position of maximum clearance while at the same timeallowing them to freely move towards the latter.
 11. A device accordingto claim 9, wherein each bent bearing plate is made rigid by itsprojecting bend with a rod normal to its surface and located in thebisecting plane of said dihedron and mounted freely slidable in saidcentral punch-carrying block, said rod comprising means for stopping itsoutward motion, constituted by a flange projecting radially, adapted tomake contact with a similar stop means rigid with said centralpunch-carrying block, both rods being arranged on either side of saidcentral punch-member.
 12. A device according to claim 1, saidpunch-members being substantially symmetrical with respect to thebisecting plane of said dihedron.
 13. A device according to claim 5,wherein automatic return means are provided to simultaneously move saidhalf-dies back to their initial position of maximum clearance.
 14. Adevice according to claim 9, wherein each intercalated plate isconnected to the bearing plate of the associated blank hold-down clamps,so as to automatically move away from said die during the withdrawal ofsaid hold-down clamps, while at the same time being freely movable inparallel relation to said bearing plate.